The present disclosure relates to a light emitting device, a light emitting device package and a lighting system.
A Light Emitting Diode (LED) is fabricated using a P-N junction diode which has characteristics of converting electric energy to light energy. Herein, the P-N junction diode may be formed by compounding elements of group III and group V of the periodic table. The LED may emit various colors by adjusting a composition ratio of compound semiconductors.
Meanwhile, according to the related art, there is a problem that a current inversely flows when Electrostatic Discharge (ESD) occurs so that an active layer which is a light emitting region is damaged.
For solving this problem, according to the related art, a zener diode is mounted to a package being inversely connected to the LED in parallel for preventing the damage of the LED due to the ESD. Accordingly, the current flows to the LED for emitting light when a constant voltage is supplied, but the current flows to the zener diode when the ESD occurs so that the LED damage due to the ESD may be prevented.
However, according to the related art, since the zener diode is mounted to the package, there is a problem of reducing light absorption.
Further, in a vertical-type LED according to the related art, an N-type electrode and a P-type electrode are formed above and below respectively for injecting the current. Herein, electrons and holes respectively injected by the N-type electrode and the P-type electrode flow to the active layer and combine with each other to generate light. The generated light is emitted to the outside, or it is reflected by the N-type electrode causing an internal loss of the light. That is, according to the related art, since the light emitted under the N-type electrode is reflected by the N-type electrode, efficiency of emitting light is reduced. Moreover, according to the related art, due to resorption of the reflected light, heat is generated.
In addition, according to the related art, a lifetime is shortened and reliability is degraded due to current crowding.